//第一步，創(chuàng)建URL
NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do?type=focus-c"];
//第二步，通過URL創(chuàng)建網(wǎng)絡(luò)請求
NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
//NSURLRequest初始化方法第一個參數(shù)：請求訪問路徑，第二個參數(shù)：緩存協(xié)議，第三個參數(shù)：網(wǎng)絡(luò)請求超時時間（秒）
其中緩存協(xié)議是個枚舉類型包含：
NSURLRequestUseProtocolCachePolicy（基礎(chǔ)策略）
NSURLRequestReloadIgnoringLocalCacheData（忽略本地緩存）
NSURLRequestReturnCacheDataElseLoad（首先使用緩存，如果沒有本地緩存，才從原地址下載）
NSURLRequestReturnCacheDataDontLoad（使用本地緩存，從不下載，如果本地沒有緩存，則請求失敗，此策略多用于離線操作）
NSURLRequestReloadIgnoringLocalAndRemoteCacheData（無視任何緩存策略，無論是本地的還是遠程的，總是從原地址重新下載）
NSURLRequestReloadRevalidatingCacheData（如果本地緩存是有效的則不下載，其他任何情況都從原地址重新下載）
//第三步，連接服務(wù)器
NSData *received = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *str = [[NSString alloc]initWithData:received encoding:NSUTF8StringEncoding];
NSLog(@"%@",str);

//第一步，創(chuàng)建URL
NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do"];
//第二步，創(chuàng)建請求
NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
[request setHTTPMethod:@"POST"];//設(shè)置請求方式為POST，默認為GET
NSString *str = @"type=focus-c";//設(shè)置參數(shù)
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
[request setHTTPBody:data];
//第三步，連接服務(wù)器
NSData *received = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *str1 = [[NSString alloc]initWithData:received encoding:NSUTF8StringEncoding];
NSLog(@"%@",str1);

//第一步，創(chuàng)建url
NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do?type=focus-c"];
//第二步，創(chuàng)建請求
NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
//第三步，連接服務(wù)器
NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];

//第一步，創(chuàng)建url
NSURL *url = [NSURL URLWithString:@"http://api.hudong.com/iphonexml.do"];
//第二步，創(chuàng)建請求
NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
[request setHTTPMethod:@"POST"];
NSString *str = @"type=focus-c";
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
[request setHTTPBody:data];
//第三步，連接服務(wù)器
NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];

//接收到服務(wù)器回應(yīng)的時候調(diào)用此方法
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
NSHTTPURLResponse *res = (NSHTTPURLResponse *)response;
NSLog(@"%@",[res allHeaderFields]);
self.receiveData = [NSMutableData data];
}
//接收到服務(wù)器傳輸數(shù)據(jù)的時候調(diào)用，此方法根據(jù)數(shù)據(jù)大小執(zhí)行若干次
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
[self.receiveData appendData:data];
}
//數(shù)據(jù)傳完之后調(diào)用此方法
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSString *receiveStr = [[NSString alloc]initWithData:self.receiveData encoding:NSUTF8StringEncoding];
NSLog(@"%@",receiveStr);
}
//網(wǎng)絡(luò)請求過程中，出現(xiàn)任何錯誤（斷網(wǎng)，連接超時等）會進入此方法
-(void)connection:(NSURLConnection *)connection
didFailWithError:(NSError *)error
{
NSLog(@"%@",[error localizedDescription]);